278 Mhz Satcom Relays

[zguy1243]

For the past week myself along with a group of other satcom monitors have been listening to a very out of the normal occurrence. There has been a active downlink from a unknown satellite that is spewing signals from ground stations and aircraft across a 1 MHz wide groupp of frequencies, +/- 500Khz from 278.000 MHz. These signal are especially interesting because they are outside the normal 250-270MHz satcom downlink band. These were first discovered by a member of the Hearsat group, a incredibly knowledgeable group of satellite monitors. Most active relays are:

278.000 AM- unknown ground control (lots of NAVY calls)
278.400 AM- Boston and Memphis Center UHF ARTCC
278.425 AM- unknown ARTCC controller
278.200 AM- Crypto
278.000 AM- BANKROLL 61 in the clear in comms with "63" (Navy E-2C Hawkeye in the afgan area)
278.050 AM- Arabic singing in WFM mode

The signals have been audible in Europe and the US. They come and go. Unsure if its a geostationary satellite or not. Also some are debating that it may be a old satellite in a graveyard orbit. Take a listen and see if you hear anything it sure a great opportunity to hear some distant and rare signals from thousands of miles away....

 

[brandon]

Great logs! Wish I was in range to pick them up.

 

[CalebATC]

Jody, are these continuous relays or are they only at certain times? I will give it a try here whenever the snow lightens up and I can hook up the HT.

Great catch!

 

[brandon]

I just read the post on Hearsat about somebody hearing Los Angeles Center, so maybe there is hope for us on the west coast. One guy on that forum said they were pointed north.

 

[brandon]

You probably already saw this but in case anyone else hasn't, the UHF-Satcom website has an interesting page up about these 278MHz links

 

[SCPD]

Anybody have any info on 244.8750 AM? Ive been picking up air traffic control on this freq during UHF satcom band searches. Is this a satcom freq or a part of the air band?

 

[CalebATC]

Going to try to get my X Wing back outside tomorrow. Are these still going on? I will report back tomorrow if possible.

Poor coordination by the Russians for sure!

Try your milair antenna, and try your SATCOM antenna. If you are getting the signal better on the SATCOM, chances are it is a downlink. You should see quite a signal difference between the two using the X Wing.

 

[SCPD]

Going to try to get my X Wing back outside tomorrow. Are these still going on? I will report back tomorrow if possible.

Excellent! Are you going to leave it outside permanently or use it as a portable antenna?

Try your milair antenna, and try your SATCOM antenna. If you are getting the signal better on the SATCOM, chances are it is a downlink. You should see quite a signal difference between the two using the X Wing.

Good idea...I should have thought of that.Brain fart I guess.lol.
Question,Is AM mode down link commonly found in use on these birds? And if so which ones are known to operate in this mode.

 

[eorange]

Anybody have any info on 244.8750 AM? Ive been picking up air traffic control on this freq during UHF satcom band searches. Is this a satcom freq or a part of the air band?

It's possible you're hearing an image. I can hear NOAA weather radio plain as day on my VR-500 somewhere in the 250.xxx range.

 

[SCPD]

It's possible you're hearing an image. I can hear NOAA weather radio plain as day on my VR-500 somewhere in the 250.xxx range.

You know..now that you mention it eorange...the traffic I have monitored was mostly related to Boston center and New York which are totally in range of my location so the signals Im getting may very well be just local air traffic bleeding over on 240Mhz. Im going to have to monitor the VHF air band on one radio and 244.8750 on another and see if I find a match up. Thanks!

 

[eorange]

Start with a simple divide by 2 (i.e. around 122.xxx MHz). The discovery of images has disappointed me many times.

 

[CalebATC]

Or, it could be a UHF center frequency. I believe the birds do some type of a any mode repeat, whatever mode they detect is whatever the satellite repeats in.

Anyway, it could be a second harmonic too. Give the SATCOM/Milair antenna a try, and do the half harmonic as eorange said.

I'll put my X Wing in the yard later, stuck home from school with a fever, cough, and a bunch of other crap.

 

[uhf-satcom.com]

Meridian-2 satellite

Evening all,

The uplink frequencies to the satellite have been worked out based on the traffic, but there is some concern that if they are made public, the satellite will fall victim to pirate operators, just as the UHF milsats have. The uplink for the satellite is however not 2nd harmonics, it is a primary UHF frequency for the air traffic control centres that are relayed. The satellite is almost a typical bent-pipe transponder so what ever mode is received, is simply re-transmitted. I've put a couple of sound recordings from M2 up at uhf-satcom.com sounds page!

We're monitoring M2 on a daily basis in the #hearsat IRC chat channel, you can get to that by going to JavaChat

regards,

Paul.

 

[CalebATC]

Evening all,

The uplink frequencies to the satellite have been worked out based on the traffic, but there is some concern that if they are made public, the satellite will fall victim to pirate operators, just as the UHF milsats have. The uplink for the satellite is however not 2nd harmonics, it is a primary UHF frequency for the air traffic control centres that are relayed. The satellite is almost a typical bent-pipe transponder so what ever mode is received, is simply re-transmitted. I've put a couple of sound recordings from M2 up at uhf-satcom.com sounds page!

We're monitoring M2 on a daily basis in the #hearsat IRC chat channel, you can get to that by going to JavaChat

regards,

Paul.

Interesting, I saw those recordings on your site.

Is this part of a new bandplan for the M2? Looks like the Russians are going to need to do some more coordinating on the bandplan.

 

[mancow]

Caleb you will probably need a yagi and preamp to hear much but it's still worth a try.

 

[CalebATC]

Caleb you will probably need a yagi and preamp to hear much but it's still worth a try.

I actually did get a few ATC calls on it earlier, barley readable, and that's with a 16db preamp. When I get this X Wing up on the tower, it should do quite a bit better.

 

[SCPD]

Forgive me but Im new to this UHF satcom stuff...anyway how often does the orbit of the Meridian-2 space craft bring it over the United States? Also if it is over the United States I would guess that we should all hear it with little trouble providing you are within its radio footprint. Is the space craft transmitting its signals in AM or WFM mode?

Also I found this live satellite tracking site that has Meridian-2.
LIVE REAL TIME SATELLITE TRACKING AND PREDICTIONS: MERIDIAN 2

 

[CalebATC]

Meridian-2 is using the bent pipe principle, whatever comes in is what goes out, unlike a FM 2 meter repeater that only does FM.

It is in the Molniya orbit - Wikipedia, the free encyclopedia , so it hovers over Russia and the US to maintain better power settings; it would be quite hard to keep it geostationary over Russia. It hovers over the US for 8 hours each day (and Russia for 8 hours a day, that's why there is three satellites to give Russia full time coverage while the other two are transitioning) And that is when the uplinks are fed by ATC frequencies from ZDC center, and a few other ATC frequencies.

 

[brandon]

Figured I would give it a try early this morning to see what I could hear
About 5-6 freqs logged but can only remember a couple right now since it was 3am
278.000 sounded like a ground controller for unknown airport.
278.200 open carrier
278.400 unknown "center"
I will try again tonight and take some better notes.

 

[zguy1243]

277.600 MHz AM mode at 531pm local here in north Georgia is active with a relay from M2 of US Mil F-16's (self id'd) with unknown ground station with a accent of sorts. Very nice signals from the F-16's. Also as I type it sounds like more aircraft on 277.725. Most of the time it is just ground station relays. These relays from aircraft are more rare and seem to have much better signal strength.